1. Field of the Invention
The present invention generally relates to systems for transporting and sorting articles and, more particularly, to arrangements for tracking of articles in such systems and having an architecture readily adaptable in accordance with various configurations of such systems and modifications thereto.
2. Description of the Prior Art
Many manufacturing and service industries rely on the ability to transport and sort materials and articles. For example, in manufacturing and numerous other applications, objects must often be transported with substantial positional precision for various operations such as container filling, labeling, part installation, packaging and sorting by customer or order destination.
One current and particularly demanding application is that of mail or package sorting for large numbers of intermediate or final destinations or the processing of financial documents such as personal checks, where both the number of articles and the number of potential categories into which the articles must be sorted are very large and accounting for each article handled is of very high importance, particularly when any sorting machines may be subject to some types of article handling errors.
While the principal function of machines adapted to such an application is principally sorting and transport is largely incidental, the locations receiving each sorted category of article (e.g. each intermediate or final destination) must be of substantial size to receive the articles and the machines must generally be very large and the transport path must be very long to accommodate the number of receiving stations corresponding to the respective sort categories.
Also, to accommodate large volumes of articles, often reaching input rates of sixty thousand articles per hour, transport speeds must be very high. Therefore, apparatus such as optical character recognition, bar code readers and the like must function accurately at very high speed to achieve the desired sorting at article velocities reaching two hundred inches (about seventeen feet) per second or more. To achieve accurate and precise handling and tracking of individual articles during the sort process, the position of articles must be accurately known while the high article speed generally prevents use of provisions which could maintain the position of an article relative to the transport arrangement. For example, pinch belt mechanisms provide for the belts to be driven at slightly different speed to avoid overlapping of flat articles but, by the same token, rely on a degree of slippage between articles and the belts. Therefore, extremely high performance is required from numerous optically-based sub-systems to support such sorting machines.
Photocells, switches and various sensors and arrays thereof are generally used to gather data for real-time control of such sorting machines and provide identification of individual articles and the instantaneous position on the transport is of paramount importance. However, any such sensors are susceptible to developing signals by detection of non-article related events such as ringing or bouncing upon change of state. In a sorter, it is necessary to know when to read indicia and to know the position and precise identification of the article in order to scan its data, read its text, print data on it, apply labels to it, stamp it, make a microfilm exposure and the like as well as when to divert the article to a bin or other receiving station, particularly as an incident of reducing effects of sensor noise. That is, if the operation of sensors can be suitably limited to the period of time in which an event of interest will occur, the amount of noise and false data signals can, in theory, be substantially reduced and accuracy of article handling and reliability of sorting be improved.
Unfortunately, two major problems militate against realization of such an improvement. First, the necessary characteristics of the article conveyor can cause the article to lose registration with a location on the conveyor which may have been detected at a given point in time. Such physical factors include variability of motion of the article along the conveyor, varying physical characteristics of the articles (and their respective aerodynamics, dimensions, thickness, rigidity and the like), varying sizes of gaps between articles, overlapping of flat articles and the loss of articles from the conveyor. Therefore, there is a limit on the degree to which acceptance of signals from sensors can be limited and noise reduced without compromising the collection of good information and the confidence which may be accorded data which is collected.
Second, any inaccuracy or detected change in tracking (e.g. detection of a given article at a sequence of locations over time in a machine which is necessarily subject to spurious events, jamming, articles of unanticipated dimensions, lost or unexpected articles, change of length of articles and the like) of a given article may raise uncertainty as to article identification and cause large errors in sorting accuracy while sensor noise may engender errors as to article location and engender ambiguity in error reporting and incorrect error recovery. Loss of an article from the conveyor or common handling of overlapping or inadequately spaced articles which should be differently sorted after the sort identification is made could result in a large volume of articles being misdirected during the sort. Different types of errors may not be adequately distinguishable or even detectable. That is, errors may not be reliably detectable and, when errors are detected, the diagnostic capability is limited to high-level distinctions between error characteristics, limiting any diagnostic or error reporting, logging and recovery capability that may be employed in regard to detected errors.
Additionally, as a practical matter, object detection with sensors in accordance with fixed locations on conveyor apparatus necessarily involves substantial hardware dependencies. That is, at any given point in time, a given photocell will correspond to a given location on the conveyor apparatus and that location on the conveyor apparatus will correspond to another photocell or other structure (such as a sorting station and bin or other synchronized peripheral device such as a printer or display) at another point in time. Therefore, the software controlling the sorting machine must be customized to each particular installation since large-scale sorters will generally be tailored or specialized to particular applications. Moreover, systems must be calibrated by the software for given operating conditions that may, in fact, vary over time.
By the same token, an additional practical problem with large-scale sorting machines is that increasing volume and numbers of sort categories also requires increase of size or other modifications of many such machines from time-to-time to provide adequate efficiency in other parts of the delivery process, such as expansion or restructuring of carrier delivery routes and the like. Thus, any modification, either structurally or operationally, requires development and custom installation of specially adapted software corresponding to both the sorter hardware configuration and its mode(s) of operation. Thus, the software development and maintenance results in substantial increases in initial and ongoing costs on different and disparate machines, slows time to delivery of new machines and increases the difficulty, time and cost of in-field changes to existing machines.
Concomitantly, current large-scale sorting systems lack fully integrated software tools to facilitate new system configuration, calibration, modification, maintenance and management. Such activities may entail time-consuming and costly software and hardware modifications.
It is therefore an object of the present invention to provide accurate and precise tracking of every article presented to an article handling machine together with full accounting and auditing with full error reporting and logging for error recovery.
It is another object of the invention to provide a hardware-independent article tracking system suitable for integration with a sorting apparatus or system and to provide a tailorable software object to encompass plural modes of operation to accommodate many variations of system configuration and modification.
It is yet another object of the present invention to provide a reduction in software development and installation time and cost for disparate or different sorter machines and modifications thereof.
It is a further object of the invention to provide increased accuracy of article tracking and error reporting and low-level embedded diagnostics and error recovery in an article transporting and/or sorting system.
It is another further object of the invention to provide a self-calibrating article tracking system which is adaptive to changing operating conditions.
It is another object of the invention to provide a system for controlling an article transport and/or sorting apparatus controllable by generalized software which can simply and easily be configured to a specific installation using a graphic user interface.
It is a yet further object of the invention to provide graphical user interfaces (GUIs) to facilitate configuration, calibration, modification, maintenance and management of an article tracking system.
In order to accomplish these and other objects of the invention, a software object is provided including an input for receiving digital information from a sensor, a data input for connecting it to other like objects, and an arrangement for selectively reporting conditions corresponding to the digital information based on signals derived from the data input. These software objects can be used singly or to form a tracking chain or chains and, in either case, provide high accuracy of article identification and position tracking in transport mechanisms such as those associated with large scale sorters. The expected time of an article related event is predicted based on an adaptive fuzzy bracket which is self-calibrating and can shift or change in size, depending on whether a particular event or an accumulated average of events is earlier or later than expected. This software object will be referred to herein as a softcell.